1. Field of the Invention
The present invention relates generally to the field of table saws, and more specifically to a computer-controlled table saw and method, including a conveyer track having support rollers for delivering pieces of lumber or other material to a table, an arm member extending over the track for positioning the pieces to be cut at a desired length, two pneumatic clamping elements which drive and hold each piece against a stop wall at the rear of the table, a circular saw mounting structure including a saw supporting arm member movable horizontally over the table with a hydraulic cylinder, motor and gear means underneath and supporting the saw mounting structure for rotating the saw mounting structure to orient the saw for each cut, an ink jet printer device for marking the pieces after they are cut and a track exit segment, a safety mat in front of the table for retracting the saw when a person stands on the mat, and a control panel tied into a computer having a program which controls the operation of the arm, the pneumatic clamping elements, saw, a motor for rotating the saw support structure, and a motor for moving the stop gage to the proper cutting length, so that a series of pieces placed on the track are automatically delivered to the table, cut at predetermined length and angles, labeled, and carried to a collection point.
2. Description of the Prior Art
There have long been automatic saws for reducing the manpower required to process lumber. While these saws have generally served their intended purposes, they have not been designed to be computer controlled to automatically make a variety of differently oriented cuts on the same work piece.
An example of these prior automatic saws is that of Fuglie, U.S. Pat. No. 2,664,926, issued on Jan. 5, 1954. Fuglie discloses an automatic saw mill for sawing logs and heavy timbers into boards. The logs are mounted between two chucks and cut by two separate sets of parallel saw blades mounted on a movable saw carriage. After sawing, the cut boards are automatically dropped onto a conveyer belt located below the saw blades. A problem with Fuglie is that there is no provision for making angled cuts across boards, as may be needed to construct trusses. And even if the logs could be somehow rotated to permit angled cuts, the angle could not change automatically for cuts at different angles on the same board. Another problem with Fuglie is that the person operating the saw apparatus must move dangerously close to the saw to load the timbers.
Strauser, U.S. Pat. No. 4,887,219, issued on Dec. 12, 1989, teaches a manual board cut-off saw assembly for enabling a cut-off saw operator to cross-cut several elongated boards at desired locations along their length. Strauser further permits the removal of defective sections from the boards based upon the observation of the operator. The apparatus includes several cut-off saw lines with manually activated cut-off saws for cutting the boards across each line. Each cut-off saw line has an optical measuring system and a sorter for sorting wood pieces according to their measured length, and for delivering information concerning board and wood piece lengths to a computer for storage. The computer also displays the recovery rate and production information. A problem with Strauser is that no provision is made for cutting the boards at the varying angles necessary for such applications as truss construction. Another problem with Strauser is that an operator can get dangerously close to the saw blades while they are spinning.
Hagstrom, U.S. Pat. No. 4,962,685, issued on Oct. 16, 1990, discloses a production table saw including a saw table and a storage cabinet below the saw table in which the saw is enclosed when not operating. A foot-activated pedal is provided to lift the saw blade out of the cabinet to an operating position. At the same time the pedal action causes a safety guard to move into a protective position over the blade. A problem with Hagstrom is that no provision is made for automatically making a series of varying angled saw cuts, nor for automatically measuring the cutting length of wood pieces on the saw. Thus Hagstrom is costly in man-hours to use. Another problem is that Hagstrom does not provide a large table surface or delivery means capable of handling long work pieces.
Richards, U.S. Pat. No. 5,043,907, issued on Aug. 27, 1991, illustrates a band saw apparatus and method regulated by a controller. A band saw is provided having a controller responsive to sensing signals as to operating parameters of the saw to generate a material distribution profile during a first cut of a piece of bar stock. During subsequent cuts, the controller operates control circuits for blade cutting force, blade feed rate, and blade speed to maintain a constant material cutting rate despite changes in material cross-section. A problem with Richards is that, once again, no provision is made for automatically making a series of varying angled saw cuts. Furthermore, no safety provision is apparently made for shutting off power to the saw when the operator is close to it.
Steiner, U.S. Pat. No. 4,641,557, issued on Feb. 10, 1987, teaches an electronically controlled power saw for making a number of different types of cuts on a work piece. A microcomputer is provided into which certain cut parameters are preset, such as saw elevation relative to the work piece. Yet for angled cuts, the arm on which the saw is mounted is swung into position manually for each cut. The microcomputer simply measures and displays the miter or bevel angle to aid in manually positioning the saw. A problem with Steiner is that angled cuts cannot be preprogrammed, but must be manually set up, one at a time. Steiner is thus relatively time-consuming to operate, and no continuous work piece feed is provided. Another problem, once again, is that the operator can move dangerously close to the saw while it is activated.
It is thus an object of the present invention to provide an automatic table saw apparatus which reduces labor costs with substantial computer control and operation.
It is another object of the present invention to provide such an apparatus which increases the accuracy of individual cuts and thereby reduces the number of re-cuts required, and eliminates undetected mis-cuts.
It is still another object of the present invention to provide such an apparatus which reduces set up time for a random mix of cuts and automatically schedules and tracks the pieces cut, to reduce inventory time.
It is finally an object of the present invention to provide such an apparatus which reduces the danger involved for the operator by permitting full operation several feet away from the saw table and automatically retracting the saw away from the operator when the operator moves too close to the saw table.